Cisco Headend System Release 2.7 Technical References
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Introducing OCAP
738184 Rev B
Signal and Delivery Process
Overview
The signaling and delivery process sends files (applications or data) over a cable
network. The applications are then launched by the OCAP implementation
(middleware) and delivered by the OCAP object carousel.
Different signaling methods are used for bound and unbound applications. The
Different signaling methods are used for bound and unbound applications. The
Applications Information Table (AIT) method is used for signaling bound
applications. Unbound applications use the XAIT for signaling.
Bound applications are usually delivered through a QAM. Unbound applications may be
Bound applications are usually delivered through a QAM. Unbound applications may be
delivered through a QAM or through DOCSIS TFTP. Another carousel may be delivered
through the OOB channel, but this is usually for data delivery.
AIT Method
The AIT is carried in the same QAM inband transport stream as the content to which it
is bound. The AIT is defined in the Program Map Table (PMT) of the associated data
content.
Because bound applications are associated with specific content, the AIT is
Because bound applications are associated with specific content, the AIT is
transmitted on the same transport stream as the content, which should also include
the object carousel (but is not required). This is similar to how MHP is implemented.
XAIT Method
The XAIT is carried over the OOB channel with the service information data. The
unbound application is delivered in either the IB or OOB stream, or the unbound
application is carried through DOCSIS TFTP.
Note: Due to the low bit rate of the OOB stream, Cisco does not recommend
Note: Due to the low bit rate of the OOB stream, Cisco does not recommend
delivery of unbound applications through the OOB stream.